Hyrovane 13 Compressor Cutting Out

[adamWatson]

Hi

I've got a Hydrovane 13 compressor that won't run. It starts and runs for about 10-15 seconds then the overload on the contactor trips. The guy I got it off sold it as he had a really poor power supply in his shop and it struggled. We thought maybe it had burnt out the relay or contactor so replaced them to no avail. I'm thinking the motor capacitors now. It starts fine and spins long enough to just start producing air. Does that suggest the start capacitor is OK and its the run that needs replacing? Edit: its a 3hp 240v single phase motor
Thanks
Adam

Sent from my GT-I9505 using Tapatalk

 

[MacMcMacmac]

If the motor is rated for 240V, and you are supplying it 220V, you are already working with an 8% undervoltage condition, unless it is rated for multiple voltages like 208/220/230/240 as stated on the name plate. As the motor starves for voltage, the amp draw will rise, maybe enough to trip the heater on overload, especially if it is sized to work with the unit at 240V. Factor in any voltage drop in the system, and the problem only gets worse. I have seen compressors trip out on high current draw running at 190V for a 230V rated motor.

The capacitors are a good place to start if the voltage is within acceptable limits under load. I have seen them powder to dust after awhile. Sometimes the metal lugs get loose under the caps as well. Make sure you discharge any capacitor before removing it from the motor by shorting the leads. The little caps inside a digital camera bite pretty hard, motor caps can kill you.

Is your discharge valve opening? What is the pressure at on the gauge when the overload trips? Hydrovanes will pressurize their cases pretty quickly, and if the inlet valve controls are sticky, and the minimum pressure valve isn't opening, they could go into an overpressure/overload condition pretty quickly, especially if someone has messed around with the safety relief valve to force it to make more pressure. Hydrovanes are not high pressure machines. The older ones were rated up to 120psi. Some of the later ones were good for 150.

Is the case venting properly when it shuts down? It may be starting against pressure. There are some small oil relief valves located on the stator of the compressor which allow oil to drain from the compression chamber at shutoff, so that the rotor will not hydrolock on startup. If these are not functioning properly, you might be overloading the motor as well.

Is rotation correct?

Have you measured the amp draw while it is running?

 

[adamWatson]

Thanks for all the information. The motor is 220-240v - standard UK mains voltage. I popped the minimum pressure valves out and cleaned it and give it a little lube with WD40. The pressure gauge gets to about 80-90psi before it trips. It has worked for my friend before I bought it and hasn't had anything done to it since. I have no way of measuring the current draw but the trip is set to 18a as the motor plate says it should draw 14.8 if memory serves me correctly. When it shuts down I can hear a hissing and the pressure gauge drops to 0 over a minute or so, is that correct?

Sent from my GT-I9505 using Tapatalk

 

[MacMcMacmac]

Thanks for all the information. The motor is 220-240v - standard UK mains voltage. I popped the minimum pressure valves out and cleaned it and give it a little lube with WD40. The pressure gauge gets to about 80-90psi before it trips. It has worked for my friend before I bought it and hasn't had anything done to it since. I have no way of measuring the current draw but the trip is set to 18a as the motor plate says it should draw 14.8 if memory serves me correctly. When it shuts down I can hear a hissing and the pressure gauge drops to 0 over a minute or so, is that correct?

Sent from my GT-I9505 using Tapatalk

Yes, the hiss is the pressure being relieved from the separator chamber back through the oil return valves, to the inlet valve area of the compressor. The case pressure should relieve itself fairly quickly. I once made the mistake of pulling the drain plug on a Hydrovane 13000 before the case had blown down and got a shower of 200F oil at 100 psi all over me.

Some days are diamonds..

 

[MacMcMacmac]

I'd be tempted to split the compressor from the motor and see if the motor is turning freely.

I'd also check the wiring in the junction box on the motor to make sure there were no loose connections.

Do you have any electrician friends who could do an amp draw test with a clamp meter?